This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator. The prevalence of obesity in the United States has steadily increased in both adults and children over the past three decades and has currently reached epidemic proportions in both sexes and all racial groups [1-4]. The association between chronic obesity and the subsequent development of hypertension and diabetes mellitus type ii is well established in adults [5]. These obesity-related co-morbidities are currently the leading two causes of end stage renal disease (ESRD) in the adult population. Despite these links to ESRD, obesity is not traditionally identified as a risk factor for renal disease, and its direct effects on renal function are not well understood. Proteinuria was first reported in obese adults over thirty years ago [35]. Subsequent case reports [24, 35, 36], case series [24, 37], and autopsy series [10, 25] have further described associations between proteinuria and obesity. Growing data suggests that proteinuria is not only a marker of renal disease but is also an effector of renal injury. This is supported by a number of experimental models of diet-induced obesity in animals which demonstrate proteinuria as well as renal functional and structural adaptations in glomeruli and the tubulointerstitium. Multiple prospective studies have recently demonstrated that proteinuria is a strong, independent predictor of progression of chronic glomerulopathies [29-33]. Furthermore, the rate of decline in renal function and progression to ESRD significantly decrease with amelioration in proteinuria [34], suggesting that early detection of proteinuria and its amelioration can help preserve renal function for a longer period of time. The clinical implications of this are manifold as current screening practices for proteinuria rely on infrequent urine dipstick analysis. Despite the growing epidemic of childhood obesity, the American Academy of Pediatrics currently recommends screening urinalyses only twice in childhood [26], making it difficult to establish the true prevalence of proteinuria in the obese U.S. pediatric population. Only one study has examined the difference in urine protein excretion between obese children versus lean counterparts [38]. While this study demonstrated a higher level of proteinuria in the obese group versus the lean group, no prevalence data was reported. To date, there has been no large scale, systematic study examining the prevalence of proteinuria in obese children and adolescents. ?? ?? The overall objective of this study is to determine whether there is an association between increased body mass index and proteinuria. We hypothesize that the prevalence of pathologic proteinuria will be higher in overweight adolescents when compared with lean adolescents. The aim of the study is to determine the prevalence of pathologic proteinuria in overweight adolescents. This is a cross-sectional study pilot designed to determine the prevalence of pathologic proteinuria in overweight adolescents, ages 12 to 21 years, seen in the Adolescent Health Center which are affiliated with Children's National Medical Center. Upon study enrollment, each participant will undergo standardized height and weight measurements. The participant's body mass index (BMI) will be calculated and BMI percentile for sex and age will be determined using the Centers for Disease Control and Prevention guidelines. Those participants with a BMI 95th percentile for sex and age will be categorized as overweight. A minimum of one and maximum of two urine samples will be collected per participant for the duration of the study. The first urine sample will be obtained at the time of recruitment. Comparisons will be made between values obtained from lean versus overweight adolescents to determine whether there is a higher prevalence of pathologic proteinuria in the study population.